Diocletian

Diocletian (245-313), Emperor of Rome (284-305), who reformed the administrative machinery of the empire, introducing the two-tiered system of augusti and caesars.

Diocletian was born Gaius Aurelius Valerius Diocletianus of humble parents in Dalmatia and became an officer in the Roman army. When Emperor Marcus Aurelius Numerianus died in 284, Diocletian's troops proclaimed him emperor. Carinus, the brother of Numerianus, contested the claim and defeated Diocletian's forces in battle in Moesia in 285 but was killed by one of his own officers, and Diocletian's rule was assured. He was immediately faced with uprisings in many parts of the vast empire and selected as his colleague a Pannonian officer, Marcus Aurelius Valerius Maximianus, better known as Maximian, giving him the title of caesar in 285 and of augustus in 286. In order to obtain more assistance in defending and administering the empire, and also in order to assure a peaceful succession to the throne, Diocletian selected two more colleagues in 293, each with the title of caesar. He adopted one of them, Gaius Galerius Valerius Maximianus, better known as Galerius, as his son; Maximian adopted the other, Constantius I. The empire was divided into 101 provinces, grouped into 12 larger divisions, each called a diocese, and into 4 major parts, over each of which a caesar or augustus was placed. All edicts were signed jointly by the four rulers, but the superior rank of the augusti and the supremacy of Diocletian over the others were retained.

The fourfold division facilitated the maintenance of order; victories over enemies of Rome in Africa and in Persia extended the boundaries of the empire, which subsequently were strengthened and fortified. The administrative reorganization of the empire resulted in the centralization of control, on an equal basis, over all its vast territories, and correspondingly ended forever the primacy of Italy. Rome was replaced as capital city of the empire by Mediolanum (present-day Milan) in Italy, the headquarters of Maximian; Nicomedia in north-west Asia Minor, the capital of Diocletian; Augusta Trevirorum (present-day Trier) in Germany, where the rule of Constantius was based; and Sirmium (Sremska Mitrovica, in what is now Serbia) in Pannonia, the administrative centre of Galerius. Despite the fourfold division, organization became increasingly autocratic. Diocletian introduced Eastern ceremonies into his court and adopted the appellation of Jovius (a form of the name Jupiter), assigning to Maximian that of Heraclius (from Hercules). His regulations were rigid and oppressive, especially the so-called Edict of Diocletian (301), which fixed the maximum prices of commodities and wages throughout the empire. The edict proved unenforceable, however, and was soon abandoned. Harsh changes in the system of collecting taxes proved more lasting. They made civil officials responsible for payment of fixed sums, leaving officeholding in the hands of the most rapacious citizens and laying the basis for peonage and serfdom. Diocletian's reign is especially remembered, however, for the renewed persecution of Christians, which he authorized beginning in the year 302. Three years later he abdicated his power and forced Maximian to follow suit, leaving the succession, as he had planned, to Galerius and Constantius. Diocletian retired to his country estate at Salona, in Dalmatia.